Age resisting vulcanized rubber compound



UNITED STATES PATENT OFFICE AGE RESISTING VULGANIZED RUBBER COMPOUND Winfield Scott, Nitro, W. Va., assignor to The Rubber Service Laboratories 00., Akron, Ohio, a corporation of Ohio No Drawing. Application May 12, 1928, Serial No. 277,392

6 Claims. (01. 18-50) The present invention relates to the manufac- Bierer-Davis aging test and produces an effect ture of a vulcanized rubber product by an imon a vulcanized rubber stock comparable with proved process wherein there is employed, in adthat resulting from several years of natural aging dition to the ordinary compounding ingredients, of the rubber.

a new type of reaction product capable of im- One example of my preferred type of com- 60 parting age resisting or anti-oxidant oharacterpounds, for example, acetone anile, was preistics to the rubber product. pared by refluxing substantially equi-molecular It is well known in the art to which this inproportions of acetone and aniline for approxivention pertains that the use of certain organic mately 40 hours in the presence of a small quancompounds as accelerators of the rubber vulcanitity of a catalyst, for example iodine. The re- 65 zation process is practically precluded because of action product was then distilled under reduced the fact that the presence of such compounds, or pressure and the acetone anile collected between or their heat of decomposition or sulfur or other 130 and 135 C.

reaction products produced in the rubber curing Diacetone anile was prepared from cliacetone 7 l5 process, apparently cause or aid in causing a relaalcohol and aniline similarly to the above men- 70 tively rapid deterioration of the vulcanized prodtioned process, excepting that anhydrous zinc ucts. Such rubber products are said to age badly, chloride was added to the diacetone alcohol, anithat is the rubber becomes hard and loses a large line, and iodine mixture and the refluxing conpart of its resiliency, while other characteristics tinued for an additional period of approximately 20 such as tensile strength and the like are very fifteen hours. 75 detrimentally affected. It has now been found Other members of the preferred type of comthat the deterioration of the rubber compound pounds have been prepared substantially accordmay be substantially decreased and the effective ing to the first method hereinbefore mentioned. life of the product materially lengthened if there An example of one mode of operating the inbe added to the rubber compound, such comvention is illustrated by the following composi- 80 pounds as acetone anile, diacetone anile, methyl tion, wherein acetone anile is employed as an ethyl ketone anile and like compounds formed by anti-oxidant. reacting ketones on primary aromatic amines. In this and in the other examples cited, diphe- This reaction, it is thought, takes place in the nyl guanidine is used as an accelerator because following manner: it is known to produce a vulcanized rubber stock 85 that has notoriously bad aging qualities. Other 0 accelerators could, of course, be used and would R(%R+R1NH2 ROR+Hz0, produce stock of higher tensile strength.

A rubber stock was manufactured in the well where R represents an aliphatic radical and R1 known manner comprising 90 represents a single benzene ring aromatict ra-di- Parts cal. The preferred proportion of the an i-oxidam used is approximately from 2 to 5% of the g are}? rubber 2 weight of the rubber to be vulcanized. However, g e 1 8 40 if desirable, a greater or smaller proportion of '7. 95' anti-oxidant may be employed ftit aitiiiiii:::::::::::::::::::::: 3:2

The age resisting characteristics of a vulcant e e dil ascertained g f ggg g gg gg igg g g wherein The stock was then vulcanized by heatlng sheets samples of the vulcanized product are subjected the s tock the usual f f for forty and in a bomb to the action of Oxygen under pressure sixty minutes in a press mamtamed at the temand maintained for several hours at an elevated pemture glvel? by forty P of steam plfessule temperature. The treated samples are then exto the Square mch (that 15 237 P01131025 0f amined and tested and the results compared with the stock cured as set forth were e ficla y similar results obtained by testing the unaged agedby healtlng samples of the stock In an Oxygen vulcanized stock. The deterioration in properbomb for elshteen hours at a tempe ature of 90 ties suffered as a result of the oxidation treat- Emd a pressure 0f 500 pounds of Oxy n ment is indicative of the result that would nor- P Square lnch- After aglng, h Stock 513111 remally be expected from that particular stock tained the appearance and feel of a vulcanized during service. Such a test is known as the. rubber of high quality. The results obtained no upon testing the aged and the unaged stocks are as follows:

Modulus olilflas tici yin s in Hours at elongations 1 at gg Time of cure aged brfiak, elo'ngw lbs/in 300% 500% 700% Percent 40 min. at 287 F 0 157 362 1055 2830 875 D0 18 131 356 1048 1545 795 00 111111. at 287 F 0 181 420 1455 2910 830 D0 18 171 436 1508 1813 755 Parts Pale crepe rubber 80 Zinc oxide 4 Sulfur 1.8 Diphenyl-guanidine 0.8 Diacetone anile 2.4

The above stock was vulcanized by heating at 287 F. for different periods of time in a press and the vulcanized stock was then aged in the manner hereinbefore described.

The results obtained by testing the aged and unaged stocks follow:

Modllzllls 01fb clas;

tici y in sin Te Y Hours at elongations Time of cure aged brieiik eloingm lbs/in 300% 500% 700% Percent 40 min. at 287 F 0 137 308 948 2090 835 Do 18 113 267 771 1138 775 min. at 287 F 0 173 403 1535 2750 815 Do 18 141 379 1273 1615 755 A comparison showed rubber stock in which was incorporated prior to vulcanization one of many preferred type of anti-oxidants, for example diacetone anile, aged better than a similar rubber stock having incorporated therein prior to vulcanization one of the commercial anti-oxidants.

Other types of my preferred class of compounds, for example methyl ethyl ketone anile, have been incorporated in the rubber mix prior to vulcanization and on artificially aging the vulcanized rubber product, have been found to greatly lessen its deterioration.

The various examples hereinbefore set forth in detail are to be understood as illustrative only and not at all limitative of the scope of the invention. Other compounding ingredients and other proportions of ingredients than those indicated in the various examples may be employed in the manufacture of various types of vulcanized rubber products as is well known to those skilled in the art to which the invention pertains.- The invention is to be understood as limited solely by the claims attached hereto as a part of this specification, wherein the invention is claimed as broadly as possible in view of the prior art.

What is claimed is:

1. The process of manufacturing a vulcanized rubber product possessing age resistant characteristfcs, Which comprises incorporating with said product prior to vulcanization one member of a group consisting of diacetone anile and methyl ethyl ketone anile.

2. An age resisting rubber product comprising the vulcanization product of a rubber stock containing prior to the vulcanization thereof one member from a group consisting of diacetone anile and methyl ethyl ketone anile.

3. The process of manufacturing a vulcanized rubber product possessing age resisting characteristics, which comprises incorporating with said product prior to vulcanization diacetone anile prepared by reacting diacetone alcohol and aniline in the presence of a catalyst and distilling the diacetone anile so formed, and completing the vulcanization.

4. The process of manufacturing a vulcanized rubber product possessing age resisting characteristics, which comprises incorporating diacetone anile into said product prior to vulcanization and completing the vulcanization.

5. An age resisting rubber product comprising the vulcanization product of a rubber stock containing prior to the vulcaniaztion of said stock diacetone anile prepared by reacting diacetone alcohol and aniline in the presence of a catalyst and distilling the diacetone anile so formed.

6. An age resisting rubber product comprising the vulcanization product of a rubber stock containing diacetone anile prior to the vulcanization thereof.

WINFIELD SCOTT. 

